dichloro-acetic acid in methanol; dichloromethane Ambient temperature;

1: 80 percent / p-TsOH / acetone / 5 h / 25 °C 2: 60 percent / DMAP / dimethylformamide / 4 h / 90 °C 3: 1) N-methylmorpholine, ClCOOiBu / 1) DMF, 15 min, -20 deg C, 2) -20 deg C, 5 min, then rt, 15 min 4: 30 percent / acetone; H2O / 8 h / 40 °C / pH 9.2 (carbonate buffer) 5: aq. HCl / methanol / 0.25 h / Ambient temperature View Scheme

1: 51 percent / pyridine / 0.83 h / Ambient temperature 2: dichloroacetic acid / CH2Cl2 / 0.08 h 3: triethylamine / CH2Cl2; methanol / 2 h / Ambient temperature View Scheme

1: AcOH / CH2Cl2 / 4 h 2: 81 percent / dichloroacetic acid / CH2Cl2 / 0.25 h / Ambient temperature 3: triethylamine / CH2Cl2; methanol / 2 h / Ambient temperature View Scheme

hydrogenchloride in methanol 0.25 h; Ambient temperature;

1: 60 percent / DMAP / dimethylformamide / 4 h / 90 °C 2: 1) N-methylmorpholine, ClCOOiBu / 1) DMF, 15 min, -20 deg C, 2) -20 deg C, 5 min, then rt, 15 min 3: 30 percent / acetone; H2O / 8 h / 40 °C / pH 9.2 (carbonate buffer) 4: aq. HCl / methanol / 0.25 h / Ambient temperature View Scheme